Pink, No Doubt perform 'Just a Girl' duet - watch
The 'Blow Me (One Last Kiss)' star performed 'Just a Girl' with frontwoman Gwen Stefani at the iHeartRadio Music Festival.
"I just got off stage from the raddest surprise performance with No Doubt. She really is that cool. #imjustagirl," Pink tweeted about Stefani afterwards.
Pink is on course to reach number two on the UK album chart with her new LP The Truth About Love on Sunday - the day No Doubt release their long-awaited comeback album Push and Shove.
Pink recently revealed that she is a "super fan" of Lily Allen, now known as Lily Rose Cooper, with whom she collaborated on her new album.
"I met her for the first time after the song was recorded, but I'm a super fan of hers," she said. "Greg Kurstin was our common thread - he did her last album It's Not Me, It's You.
"I just met her for the first time when she came and sang that song with me on VH1 Storytellers. It was very strange to meet someone for the first time on stage, but I think she's awesome - she's so sweet."